Stuffed FTB with PreAmp, Amp and Integrator components only for testing.
No signal test. The PreAmpOut1 has a ringing ~ 10 mV. This creates a large offset at the AmpOut2
FTB_YellowPAOut2_BlueAOut2_NoSignal_49ResistorOnAmpIn2
Replaced R12 on Amp1. Reduced Amp1 gain from 40 to 2.
FTB_YellowPAOut1_BlueAOut1_NoSignal_1kResistorOnAmpIn1
MPPC Output with 70.7V Bias on U100s Serial Number 561 and 562 on 2mm by 5cm long scintilating crystals with Sr70 source.
MPPC U100s output with the Sr70 is approximately 100 mV with a 33k Ohm resistor. Current generated should be about ~ 3 uA.
Blue is readout from 561 MPPC.
Yellow is readout from 562 MPPC.
Hooking the MPPC output into the FTB's transimpedance amplifier gave about 350 mV output at the PreAmp. The TransAmp resistance is 2k which shows that the amplified current is about 175 uA. The final amplifer should give 2x that on channel 1 which correct for the Amp's configuration (2k / 1k Ohm OpAmp).
Blue is readout from 561 MPPC.
Yellow is read out from PreAmp1 using signal from 562 MPPC.
Purple is readout from Amp1.
We kept Channel 2 with the original configuration with a 40x Amplifier (2k / 50 Ohm OpAmp). 300 mV from here should give 12V output. Of course this saturates the Amplifier, but it doesn't seem saturate as fast as expected on the turn on curve. Saturation sould occur at 100 mV on the yellow curve. Which is ~ 1.5 ns after trig, but it doesn't seem to occur until 10 ns after trigger. The fall gives a better agreement between PreAmp*40 = AmpOut.
Blue is readout from 561 MPPC.
Yellow is read out from PreAmp2 using signal from 562 MPPC.
Purple is readout from Amp2.
With the appropriate choice of R+, the effects of Input Bias Current can be minimized with the resistor on the non-inverting terminal of the op amp.
Choice of R+
Blue is readout from 561 MPPC.
Yellow is read out from PreAmp2 using signal from 562 MPPC.
Purple is readout from Int2.
Schematics and Components on FTB.
FTB_PreAmp.pdf
FTB-Amp.pdf
FTB-INT.pdf
Output from Chn 3 with lowered Amplifier (x4).
400 mV (current through 33k Ohm resistor) output is PA to ~ 1 V. Then the Amp increased the output to ~ 4V.
Yellow Signal.
Blue PAOut3
Purplse AmpOut3
Channel 3 on the left, Channel 4 on the right.
Yellow Signal.
Blue IntOut3
Purplse SHOut3
The integrator's output peaks about 1 V also. While the Sample and Hold in Sampling mode has an output peaking about 200 mV. There's also a delay between the Signal and the S&H signal.
Yellow Signal.
Blue AmpOut3(4)
Purplse DiscOut3(4)
Yellow Signal.
Blue Digital Out 4
When the probe is applied to the Digital output there's a feedback which affects the signal coming out of the otherside of the SIPM.
Yellow Signal.
Blue TrigOut
This is done by putting a fake signal into the other three channels.
Channel 2 is broken so a 5 V bias is place into the discriminator output directly
Channel 3 and 4 is supplied with a 5 V / 1k current to drive the Transimpedence amplifier.
Picture of FTB with breadboard. Top SiPM is routed to trigger for the scope, the bottom SiPM output is supplied to channel 2 of the preamplifier input. Channel two still has a 40X amplifier so it's actually better to move this Channel 3 or 4 in actual test.
Picture of FTB with wires attached for readout and fake signals.
Instructions to get TrigOutput from FTB using a single SiPM signal.
Connect Ribbon with Pin 1 on the bottom left with respect to the orientation in photo.
Red Circle: Apply 5V Bias.
Blue Circle: Apply 5V / 1k current (5 mA).
Black Circle: SiPM Signal.
Yellow Circle: TrigOutput.
Daughter Cards.
Hamamatsu SiPM Pair
Daughter Card 1
Daughter Card 2
Daughter Card 3
Daughter Card 4
Daughter Card 5
June 19th 2013 Update
Final FTB2 setup with 2 SiPM readout of a 2x2mm^2 and 2 Fake Constant 5V Signal. Trigger Pulse on 4 channels coincidences Green. Amplified output from the two SiPMs in Yellow and Magenta.
Some Useful Alteration to FTB
Put SMD POT away from each other, any plastic components, any "Tall" components.
Small Through-Hole probes for PreAmp, Amp, Bias Voltage, Threshold Voltage, Integrator, (maybe also) discriminator.
Modify Integrator and Amplifier Resistance so Resistance to Ground on the Non-inverting input = Resistance of Inverting Input parallel to feedback resistor to remove bias current voltage.
We still haven't figure out how to ge the switch to work
Make the board size fit into one of these black boxes we have in the lab.
June 20th 2013 Update
First test, a Pair of Hamamatsu U50s serial number 516 and 517 with gain of 7.5e5 per photoelectron. Mounted onto the 5x5x50 mm^3 scintilation crystals with teflon and black type wrapping.
Scope traces with the Sr90 Source on the scintillator. The signal looks very clean without any coupling grease. The Amplified output is on the order of 0.5V per photon electron. The preamp output gives about 200 mV = 4V/200 as expected. Trigger is at about 2-5 Hz.
Yellow AmpOutRight
Blue AmpOutLeft
Magenta PreAmpRight
Green FTB2 Trigger
Scope traces without any Source on the scintillator. This took about 1 minutes of waiting for the trigger. Rate is ~ 0.03 Hz. This is most likley a cosmic. The signal also looks very clean.
Yellow AmpOutRight
Blue AmpOutLeft
Magenta PreAmpRight
Green FTB2 Trigger
July 9th 2013 Update
I wrapped 3 plastic optical fibers onto the scintillating puck. Each side of the fiber goes to a different SiPM. Three fibers are coupled into each SiPM.
The scintillator doesn't seem to give off light in conincidence. When I trigger off channel 1, channel 2 is basically flat and vice versa. The amount of light that I can trigger on is failry high in the dark box. This is approximately 3-4 times higher than what I was able to trigger on with 1 fiber per SiPM. We about 1.5V trigger at about 10 Hz on Channel 2 and Channel 1 gives about 2.2V Amplified Output at about 10 Hz.
Yellow Output from Channel 1 Triggering on Channel 2.
Yellow Output from Channel 1 Triggering on Channel 2.
Yellow Output from Channel 2 Triggering on Channel 1.
Yellow Output from Channel 2 Triggering on Channel 1.
July 10th 2013 Update
Due to the failure to get coincidences on the Scintillation Puck. We wanted to try two different tests.
A: Make sure that the scintillator does scintillate.
To do this we cut out a 1x1x5 cm^3 rod out of the scintillator slab and mounted two SiPM end to end as we do with the precut scintillator.
Noah and I used a band saw and fly cutter to make one of these rod in the machine shop.
Noah sanded and polished up the rough sides of the scintillator as usual.
I wrapped it up in Teflon + black tape and attached two SiPM end to end to it.
These are the initial signal we see out of the Amplifier output of the SiPM on FTB2.
The Trigger is on the order of about 10 Hz with the Beta source next to the crystal and went down to about 0.05 Hz with just cosmics.
The signal looks very clean and synchronized between the two sides.
With Beta Source.
Cosmics only.
B: Use the 0.5x0.5x5 cm^3 Scintillator as the trigger and place the puck underneath to see if the signals we're getting are from cosmics.
I made an additional voltage divider on the bread board to supply the U50 with 70.6V and U100s with 69.6V.
When I tried to test this on FTB2, channel PA2B does not respond.
Removing all the signal sources, there's a bias of 50mV on PA2B output and -1V on A2B output.
This behavior shouldn't exist and does not exist on the other three channels.
Amp2 OpAmp also heats up as the testing goes on.
There were some modification done to the board for Noah's testing purpose.
I have started assembling FTB4 with only the analog component for Scintillator testing purpose only.
July 11th 2013 Update
Characterization of SiPMs on their respective scintillators using FTB2
U100 pair on 1x1x5cm^3 scintillator rod.
Hamamatsu SiPM U100 Serial: 561
Hamamatsu SiPM U100 Serial: 562
We set the trigger threshold to various voltages and check for coincidence on both sides of the scintillator
Bias Voltage at 69.6V on both SiPM. Background are non-coincidence counts with the beta source on the scintillator
Triggering on 561 @ 0.50V - 15 Background / 20 Events
Triggering on 561 @ 0.75V - 4 Background / 20 Events
Triggering on 561 @ 1.00V - 4 Background / 20 Events
Triggering on 561 @ 1.25V - 2 Background / 20 Events
Triggering on 562 @ 0.50V - 1 Background / 20 Events
Triggering on 562 @ 0.75V - 1 Background / 20 Events
Triggering on 562 @ 1.00V - 0 Background / 20 Events
Recommended Threshold for 561 @ 1.3V
Recommended Threshold for 562 @ 0.75V
Using these threhold voltage, we trigger on coindence on both SiPM and measured the rate using the beta source and cosmics.
Beta Source: ~ 25 Hz
Cosmic: 3 coincidence / 30 seconds. 0.1 Hz.
U50 pair on 0.5x0.5x5cm^3 scintillator fiber.
Hamamatsu SiPM U50 Serial: 916
Hamamatsu SiPM U50 Serial: 917
We set the trigger threshold to various voltages and check for coincidence on both sides of the scintillator
Bias Voltage at 70.6V on both SiPM. Background are non-coincidence counts with the beta source on the scintillator
Triggering on 916 @ 0.50V - 20 Background / 20 Events
Triggering on 916 @ 0.75V - 7 Background / 20 Events
Triggering on 916 @ 1.00V - 6 Background / 20 Events
Triggering on 916 @ 1.25V - 1 Background / 20 Events
Triggering on 917 @ 0.50V - 19 Background / 20 Events
Triggering on 917 @ 0.75V - 115Background / 20 Events
Triggering on 917 @ 1.00V - 3 Background / 20 Events
Triggering on 917 @ 1.25V - 3 Background / 20 Events
Triggering on 917 @ 1.40V - 0 Background / 20 Events
Recommended Threshold for 916 @ 1.3V
Recommended Threshold for 917 @ 1.3V
Using these threhold voltage, we trigger on coindence on both SiPM and measured the rate using the beta source and cosmics.
Beta Source: ~ 100 Hz
Cosmic: 3 coincidence / 60 seconds. 0.05 Hz.
Task B for today is also testing the large scintillator slab to see why we're not getting coincidence on the puck / square scintillators.
A U100 Serial Number 563 was attached to the square scintillator on side.
The 1x1x5 Rod with two U100 are placed into the daughter card slots on FTB4.
FTB4 is then place on top of the Square Scintillator.
The Beta source is placed on top of the rod scintillator.
Yellow and Blue are the Amplified read out from the Rod.
Magenta is the Amplified read out from the Square.
Triggering is done on the yellow channel on the rod.
We see conincidence 95% of the time between all three channels.
The beta ray source was removed to see what happens with cosmics.
With cosmics, the rate went down to about 0.1 Hz as usual.
The AmpOut from the square went off the scale with 50mV/Div.
The MIP on a thicker scintillator probably gave out more light.
Square Scin. with 100 mV/Div.
Square Scin. with 500 mV/Div.
We can see that we do get conindences between all 3 channels on cosmics, but the amount of light collected by the SiPM on the square slab varies greatly. This probably caused by the amount of light loss within the crystal. This square slab was wrapped with 2 layers of Teflon + 1 layer of Aluminum foil. There might be a lot of losses due to the scratches on the sides of the scintillator since we won't have an air tight contact between the Teflon and Scintillator on most of the surface..